Communication networks, such as those used to deliver telecommunications, to interconnect computers, and the like, may include any number of nodes interconnected by communication links. The networks may deliver electronic communications between two points by routing the communications over the links from node to node within the network. As the number of nodes in a network increases and as the number of communication paths available to each network node increases, the number of potential paths available for delivering any single communication likewise increases.
Accordingly, networks often use techniques for specifying a route to follow when delivering a communication from an origination node to a destination node. These techniques can be sophisticated and are often carried out by computer analysis based upon models of the entire network. The complexity of the route specification problem and the amount of intelligence and processing power required to solve the route specification problem can force at least a portion of the route determination problem to be solved "off-line" before the communications are actually delivered through the network nodes.
However, selecting routes before communication delivery makes the network vulnerable to link failures. For example, when an off-line process evaluates the route determination problem, a particular link may be operational. Thus, the off-line process specifies the use of the particular link in various routes from various origination nodes to various destination nodes. If this particular link then fails, all communications being delivered in accordance with the off-line process specifications over routes that include the link likewise fail to reach their intended destinations.
The failure of a single link, or even several links, need not permanently impede communications because networks typically support many different routes between potential origination and destination nodes. Thus, the network's off-line route determining process may be repeated taking into account any failed link so that it no longer specifies routes that include the failed link. Unfortunately, this may be a complex and time-consuming process. Moreover, the length of time is increased when the physical configuration is dynamic, such as when network nodes are moving, so that the entire process must be repetitively performed for numerous iterations to track or otherwise simulate the node movement. An additional delay occurs when the solution of the route determination problem is then delivered through the network to all nodes prior to its implementation by the network. The delivery problem may be worse still due the inclusion of failed links in routes over which the solutions are delivered. Consequently, communications may continue to fail for an undesirable long duration after a link failure. Accordingly, there is a significant need for a network and method which respond to a failed link.